Condensate drains of this type are used for example in pressurized air technology in order to remove from the pressure line network the condensate normally produced therein, which, besides water, may also contain oil or rust. The condensates are produced from the moisture of the ambient air, which is sucked in by a pressurized air compressor in order to generate the pressurized air. The oil originates substantially from the compressors, in which it is used as lubricant, whereas the rust generally originates from the pressurized air lines.
Different designs of condensate drains are known. These generally function in such a way that a valve is opened, whereby the condensate is driven out from the pressurized air network by the pressure. With this approach, the gas loss or pressurized air loss is to be minimized for reasons of economic viability during operation of the pressurized gas system.
Known condensate drains can be divided basically into three groups in accordance with the type of valve control and the energy supply:
What are known as float drains function with a hollow body, which is raised by the buoyancy force of the liquid (condensate) collecting in a collecting chamber and thereby operates a valve. This valve opens, generally indirectly by means of a servo control, an outlet opening of the collecting chamber, through which the condensate is pushed out. The condensate drains formed as float drains are very widespread due to the fact that they can be produced cost effectively, but are also susceptible to failure.
Furthermore, condensate drains having time-controlled solenoid valves, which are electrically operated valves, are known. These condensate drains open the valves in adjustable time intervals. It is disadvantageous if the valves are opened in the absence of condensate whereby energy losses are caused as a result of the outlet of pressurized air.
Lastly, condensate drains having electronically level-controlled valves, also referred to hereinafter as electronically level-controlled condensate drains or as electronic condensate drains for short, detect a collecting liquid or condensate volume by an electronic filling level sensor. When a specific volume is reached, the valve is opened and precisely this volume is drained without additional pressurized air losses. These types of condensate drains are relatively expensive in terms of production, but are characterized by very cost-effective operation, as a result of which significant cost advantages can be achieved with the electronically level-controlled condensate drains over the entire operating service life thereof. The electronically level-controlled condensate drains have become established in the meantime as a favorable solution for draining condensate from pressurized gas systems.
An electronically level-controlled condensate drain 20 for a pressurized gas system 21, in particular a pressurized air system, according to the prior art is illustrated in FIG. 4 of the drawing accompanying this description. The condensate drain 20 has a condensate collecting chamber 22, which can be connected via a condensate inflow 23 to the pressurized gas system 21. A condensate, which then collects in the condensate collecting chamber 22 of the condensate drain 20, in particular at the base of the condensate collecting chamber 22, is thus removed from the pressurized gas system 21, for example at a lowest point of a pipeline. The condensate collecting chamber 22 further has a condensate outflow 25 that can be closed by means of an electrically operable valve 24. The condensate filling level in the condensate collecting chamber 22 is detected by means of at least one electronic filling level gauge 26, for example a capacitive filling level sensor, which protrudes in the case of the condensate drain 20 illustrated FIG. 4 into the condensate collecting chamber 22. An electronic control unit 27 evaluates the condensate filling level in the condensate collecting chamber 22, said filling level being detected by means of the filling level sensor 26, and, as soon as a specific condensate volume in the condensate collecting chamber 22 is reached, the control unit 27 opens the valve 24 in order to drain this condensate volume from the condensate collecting chamber 22. Once the condensate has been drained from the condensate collecting chamber 22, the control unit 27 closes the valve 24 again in order to avoid unnecessary pressurized air loss from the pressurized gas system 21. In the case of the condensate drain 20 illustrated in FIG. 4, the valve 24 is opened and closed by an electrically operable magnet or electromagnet 28. It is therefore an electrically operable solenoid valve.
For the operation of electronically level-controlled condensate drains, electrical energy is necessary due to the operating principle of these drains. In FIG. 4, this is illustrated by means of an electric energy supply line 29 leading to the condensate drain 20. This may be a disadvantage however depending on the installation site, for example if there are very large distances between the point at which the pressurized air is generated, which generally has an electrical energy supply, and the point at which the pressurized air is used. In such a case, a complex routing of electrical lines to the condensate drain is necessary. Also in the case of operation of the electric condensate drain in an atmosphere at risk of explosion, the electrical supply of the condensate drain and the equipment thereof, due to the possible formation of electric ignition sparks, are rather complex due to the explosion protection measures to be taken into consideration.
In the case of electronic condensate drains according to the prior art, such as the condensate drain 20 illustrated in FIG. 4, a function monitoring is also conventional. Here, an alarm signal for example is triggered via an electrical transmission line 30 leading away from the condensate drain 20 when the level of condensate collected in the condensate collecting chamber 22 remains constant in spite of the condensate discharge procedure. In particular, an alarm signal or fault signal is transmitted by means of the line 30 from the condensate drain 20 to an attendant, usually in a potential-free manner. Fault signals at the condensate drain may further also be indicated via optical or acoustic signaling devices, for example warning lights or warning sirens. In this case too, a complex wiring is necessary depending on the installation site, for example with a large distance between the condensate drain and the attendant, and the acoustic or optical warning signals are less effective.